CVE-2017-13846 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.13.1 is affected. The issue involves the third-party "PCRE" product. Versions before 8.40 allow remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact.
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Analysis
by VulDB Data Team • 09/06/2024
The vulnerability identified as CVE-2017-13846 represents a critical security flaw affecting Apple macOS systems running versions prior to 10.13.1. This issue stems from the third-party Perl Compatible Regular Expressions library, commonly known as PCRE, which is extensively utilized across various Apple products including iOS, macOS, and watchOS. The affected PCRE versions before 8.40 contain a memory management flaw that creates opportunities for remote attackers to exploit system stability and potentially execute unauthorized actions. The vulnerability manifests through improper handling of regular expression patterns during processing, creating conditions where malformed input can trigger unexpected behavior in the underlying system components that rely on PCRE functionality.
The technical implementation of this vulnerability involves buffer overflow conditions and memory corruption issues within the PCRE library's pattern matching algorithms. When applications process regular expressions containing specially crafted malicious input, the library fails to properly validate input boundaries, leading to memory access violations that can cause application crashes or system instability. This type of flaw falls under the CWE-121 category of stack-based buffer overflow, though the actual implementation involves heap-based memory corruption that can be exploited through multiple attack vectors including web browsing, email processing, and file parsing operations. The vulnerability demonstrates how third-party libraries can create cascading security issues across entire operating system ecosystems, particularly when these libraries are integrated into core system components and user-facing applications.
The operational impact of CVE-2017-13846 extends beyond simple denial of service conditions, as attackers can potentially leverage the instability to execute arbitrary code or escalate privileges within affected systems. Remote attackers can craft malicious regular expressions that, when processed by applications using the vulnerable PCRE library, trigger system crashes that may be exploited to gain unauthorized access or execute malicious payloads. This vulnerability affects a broad range of Apple applications that utilize PCRE for text processing, pattern matching, and data validation operations, including Safari web browser, Mail application, and various system utilities. The attack surface is particularly concerning because regular expressions are fundamental components in text processing operations and are commonly used in security validation mechanisms, making this vulnerability a potential gateway for more sophisticated attacks.
The remediation approach for this vulnerability requires immediate deployment of macOS updates to version 10.13.1 or later, which includes the patched PCRE library version 8.40 or higher. System administrators should prioritize patch management across all affected Apple devices, particularly those running older macOS versions such as 10.12.6 and earlier. Organizations should also consider implementing network monitoring to detect potential exploitation attempts and ensure that all third-party applications relying on PCRE are updated to versions compatible with the patched library. The vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1489 for network denial of service, as attackers can leverage the instability to cause system disruptions or potentially gain elevated privileges through exploitation of the memory corruption conditions. Additionally, the vulnerability demonstrates the critical importance of maintaining up-to-date third-party security libraries and implementing proper input validation mechanisms to prevent exploitation of similar memory corruption vulnerabilities in system components.